Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23F—COFFEE; TEA; THEIR SUBSTITUTES; MANUFACTURE, PREPARATION, OR INFUSION THEREOF
  • A23F3/00—Tea; Tea substitutes; Preparations thereof
  • A23F3/16—Tea extraction; Tea extracts; Treating tea extract; Making instant tea
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23F—COFFEE; TEA; THEIR SUBSTITUTES; MANUFACTURE, PREPARATION, OR INFUSION THEREOF
  • A23F3/00—Tea; Tea substitutes; Preparations thereof
  • A23F3/16—Tea extraction; Tea extracts; Treating tea extract; Making instant tea
  • A23F3/20—Removing unwanted substances
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23F—COFFEE; TEA; THEIR SUBSTITUTES; MANUFACTURE, PREPARATION, OR INFUSION THEREOF
  • A23F3/00—Tea; Tea substitutes; Preparations thereof
  • A23F3/16—Tea extraction; Tea extracts; Treating tea extract; Making instant tea
  • A23F3/22—Drying or concentrating tea extract
  • A23F3/26—Drying or concentrating tea extract by lyophilisation
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23F—COFFEE; TEA; THEIR SUBSTITUTES; MANUFACTURE, PREPARATION, OR INFUSION THEREOF
  • A23F3/00—Tea; Tea substitutes; Preparations thereof
  • A23F3/36—Reducing or removing alkaloid content; Preparations produced thereby; Extracts or infusions thereof
  • A23F3/38—Reducing or removing alkaloid content from tea extract

Definitions

• the present invention relates to a process of separating a tea extract into phases, particularly to a lighter coloured phase and a darker coloured phase thus obtained and more particularly to instant tea products at least partially consisting of the said phases.
• aqueous tea extracts contain a complex between caffeine and polyphenols (tea tannins) which at about 0.3 wt% solids concentration is insoluble at temperatures of below 25 C.
• polyphenols tea tannins
• tea creaming This clouding phenomenon is known in the art as "tea creaming” and this will be referred to throughout this specification and the attached claims as the natural self-separating capacity of tea extract.
• a decreaming step is employed in the manufacturing of many tea products to precipitate and remove this tea cream.
• the present invention relates to a process of separating a tea extract into phases, which comprises:
• the tea extracts used in the present invention can be obtained from at least partially fermented teas, e.g. black tea (which is preferred), oolong tea, or mixtures thereof.
• the process of the present invention can also be applied, however, to unfermented teas like green tea, in which case the separated phases have different colours and character.
• black tea When black tea is used in preparing the tea extract, it can be enzymatically pretreated with cell-wall- digesting enzymes, such as cellulase, pectinase or hemicellulase prior to extraction.
• cell-wall- digesting enzymes such as cellulase, pectinase or hemicellulase prior to extraction.
• the enzyme treated tea leaf provides a higher yield of tea extract, due to the better accessability of the leaf material for the extractant.
• the tea leaf can then be extracted in a conventional manner to provide the tea extract.
• the tea leaf material is infused in hot water with a temperature between 50 C and 100°C (and if pressure is used the temperature can still be higher) in ratio of preferably about 10% leaf and about 90% of water, followed by separation of the leaf from the resulting extract.
• the obtained tea extract has a concentration of about 3-4% by weight of tea solids.
• the extraction may be carried out batchwise or continuously.
• the obtained tea extract is subsequently concentrated, by which step the natural self-separating capacity (as hereinbefore defined) is changed.
• This concentration may be effected by membrane concentration (such as reverse osmosis), evaporation (such as rotary evaporation) during which step vacuum may be applied, or combinations of these concentrating methods, the tea extract is concentrated to 6 to 45% by weight of tea solids, and preferably to a concentration of 12 to 30% by weight of tea solids.
• the concentrated tea extract is lowered in temperature to a value below 5°C to induce phase separation.
• the phase separation may be induced in various ways.
• the concentrated tea extract may for example be placed in tall containers to effect the best passive separation with minimal interface area between the phases which develop in the extract.
• the containers with the concentrated tea extract are then cooled to a temperature below 5 C for a period of at least 5 hours. In practice periods of between 6 and 48 hours have been used, a typical value being 16 hours; the longer the period of cooling, the better the separation, but of course there are economical factors limiting the cooling period.
• the temperature range to which the concentrated tea extract is cooled is between the freezing point of the concentrated extract and just below 5°C, in other words: the phase separation is induced by bringing the concentrated tea extract into a super-cooled state.
• the concentrated tea extract is cooled and the cooled concentrated tea extract is subsequently brought into a suitable refrigerated centrifuge.
• the temperature of the treatment again is such that the concentrated tea extract is in a super-cooled state.
• the tea extract is centrifuged for a period sufficient to effect a complete separation of the two phases which are formed, viz. a light orange coloured layer and a dark brown coloured layer, which latter in this case is obtained as a pellet. Centrifugation times of 2 hours or more have proved to be very suitable.
• the phase separation is induced by freezing the concentrated tea extract.
• the rate of cooling is dependent on the concentration of the tea extract, which in this embodiment preferably is between 15 and 30% by weight of tea solids, and upon the heat transfer between the concentrated tea extract and the freezing apparatus.
• concentration of the tea extract which in this embodiment preferably is between 15 and 30% by weight of tea solids
• phase separation was induced after 1 hour. After this time the samples were frozen solid and had the appearance of a bilayer with a thin top layer having a dark brown colour and a bottom layer of light orange colour, the boundary layer between the two phases being very sharp and distinct.
• the cooling rate in general is from 0.5 to 5 C per minute and preferably from 2 to 3 C per minute.
• phase separation process according to the present invention neatly partitions tea extracts into two compositionally distinct phases with greatly different solubility and appearance.
• the one phase is from light orange to brownish in colour and accounts for approximately 60 wt% of the material after separation and this phase is indicated throughout this specification and the attached claims as "the lighter coloured phase” .
• This lighter coloured phase dissolves even in cold water (5°C) to yield an optically bright, clear solution, even at concentrations of 1% by weight of tea solids, which is about three times the normal beverage concentration.
• the beverage with this 1 wt% concentration retains its clarity upon storage at 5 C for at least two months.
• the present invention therefore also relates to a lighter coloured, isolated separated phase of a concentrated tea extract, whenever prepared by the process according to the present invention.
• the lighter coloured phase appeared to be lower in caffeine and theaflavins, but higher in salts and thearubigins.
• the lighter coloured phase is preferably converted into a particulate instant tea product by drying, optionally after a concentration step, preferably by membrane concentration.
• the drying may be spray-drying, but preferably freeze-drying.
• the present invention therefore also relates to a particulate, cold water-soluble, instant tea product, at least partially consisting of the dried lighter coloured, separated phase of a concentrated tea extract according to the present invention.
• the present invention relates to a reduced caffeine, tea based beverage comprising a lighter coloured phase according to the present invention.
• the present invention also relates to an isotonic tea-based beverage which at least partially comprises the lighter coloured phase according to the present invention.
• the other separated phase is dark brown to black in colour and throughout this specification and the attached claims is referred to as "the darker coloured phase”.
• This darker coloured phase only completely dissolves in hot water and at beverage concentrations it forms an intensily turbid, dark brown solution upon cooling.
• the darker coloured fraction was lower in salt and thearubigins, but higher in caffeine and theaflavins.
• the present invention therefore also relates to a darker coloured, isolated separated phase of a concentrated tea extract, whenever prepared by the process according to the present invention.
• this darker coloured phase is preferably converted into a particulate instant tea product by drying, optionally after a concentration step.
• the phase is preferably dried by freeze-drying.
• the present invention also relates to a particulate, hot water-soluble, instant tea product which at least partially consists of the dried darker coloured phase obtained by the process according to the present invention.
• the present invention also relates to a tea-based beverage comprising a darker coloured phase according to the present invention.
• the present invention also relates to a tea flavour composition (or a particulate tea flavour composition) at least partially consisting of the darker coloured phase according to the present invention.
• the darker coloured, isolated separated phase can be subjected again to the process according to the present invention, if desired.
• the darker coloured phase can also be used as an anti-oxidant or a colouring agent, optionally after having been subjected again to the process according to the present invention.
• the hot dilute extract obtained was concentrated by reverse osmosis to between 20-25 percent by weight of solids and the warm extract obtained (55-60 C) was placed into polyethylene bags (size: 45.7 cm x 76.2 cm (18"x30")) and heat-sealed 30.5 cm (12") from the end of the bags.
• the sealed bags with warm extract were placed under slight pressure between the cooling plates of a horizontal plate freezer (operating at -37 C) and left to freeze solid for between 30-60 minutes.
• a frozen block was obtained with a top (darker) layer and a bottom (lighter) layer, having a sharp boundary between the layers. When frozen, the thickness and solids content of the separated layers were assessed.
• the frozen tea blocks were then freeze-dried and the obtained freeze-dried block was separated into the two major fractions.
• the bottom fraction was lighter in colour and readily soluble in cold water to yield a clear solution (even up to 1% solids concentration).
• the clear 1 wt% solution when pasteurised at 85 C for 2 minutes remained clear for 3 months in a refrigerator (5-7° C).
• the darker phase, located above the lighter phase, at beverage concentration (0.3%) produced an intensely turbid, dark coloured beverage.
• Example II In both cases at the end of the treatment two distinct layers were visible with a sharp boundary between them, but here the lighter phase occured above the darker phase. The properties of both the light and the dark layer were commensurate with those of the product according to Example I. This Example also demonstrates that at chill temperatures a convenient phase separation is obtained.
• Example II An 18% by weight concentrated tea leaf infusion was prepared (using reverse osmosis) as described in Example I. This concentrate was frozen into flakes, which were subsequently freeze-dried. From this freeze-dried particulate material a series of tea solutions was prepared, having different tea concentrations, using deionised water. The different solutions were placed in tall, translucent plastic cylinders. After ensuring solubility by heating the solutions to over 90° C for 5 minutes, the samples were cooled at ambient (18° C) for 2 hours.
• the concentration range from 6-30 wt% exhibited the following proportional volume separations between light and dark phases after standing at chill (0-5 C) for 16 hours.
• the cylinders with the tea solution separated into light and dark phases were then blast frozen at -20° C for 2 hours and subsequently freeze-dried.
• the lighter coloured and darker coloured layers were separated and the lighter fractions were found to have the same properties upon dissolving in cold water as the product for the lighter fraction described in Example 1.
• the lighter fractions could be stored for more than 3 months at 5-7° C without becoming turbid.
• Three types of tea viz. black leaf tea blend, ceylon tea and oolong leaf tea were extracted with deionised water in a weight ratio of leaf to water of 1:(10-13) respectively at a range of temperatures (60-100°C) for up to 15 minutes.
• the tea leaf was then forcibly compressed and again dispersed two times during extraction and the excess dilute liquor pressed from the hydrated leaf.
• the dilute extracts obtained were then concentrated using rotary evaporation to an approximate concentration of 15wt% of solids. This concentrate was heated to over 90° C for 5 mins to ensure solubility and then cooled to 80 C before any "tar" droplets could coalesce and poured into tall plastic containers and left to cool at ambient.
• the plastic containers with tea concentrate were then placed in a refrigerator for 16-65 hours to effect the best passive separation at a low chill temperature (from -1 C to 5° C).
• Green tea leaf was extracted with deionised water in a weight ratio of 1 part tea to 10-13 parts by weight of water at 100° C in a stirred tank reactor. The mixture of leaf and water was kept in the tank for 3 minutes whilst stirring and then the contents of the tank were passed through a filter press to obtain a green tea extract of 1.5-2% by weight of solids.
• This dilute extract was cooled to about 65 C and concentrated by reverse osmosis to 16% by weight of solids.
• the concentrated extract was frozen into flakes on a cooling drum and the flakes obtained were freeze dried. From the freeze dried material obtained a series of solutions in deionised water was made, which were put into tall plastic cylinders, after having been heated to over 90 C for 5 minutes to ensure complete solubilization of the samples.
• the light fraction obtained after separation of the 40 wt% sample solution was clear after 3 months storage at 5°C.

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• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Tea And Coffee (AREA)
• Medicines Containing Plant Substances (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Compounds Of Unknown Constitution (AREA)

Applications Claiming Priority (2)

Publications (2)

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ID=10678604

Family Applications (1)

Country Status (17)

Cited By (4)

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Citations (5)

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• 1990
  • 1990-07-03 GB GB909014756A patent/GB9014756D0/en active Pending
• 1991
  • 1991-06-24 EP EP91201618A patent/EP0464919B1/fr not_active Expired - Lifetime
  • 1991-06-24 DE DE69110357T patent/DE69110357T2/de not_active Expired - Fee Related
  • 1991-06-24 DK DK91201618.5T patent/DK0464919T3/da active
  • 1991-06-24 ES ES91201618T patent/ES2074216T3/es not_active Expired - Lifetime
  • 1991-06-24 AT AT91201618T patent/ATE123626T1/de not_active IP Right Cessation
  • 1991-06-27 NZ NZ238753A patent/NZ238753A/xx unknown
  • 1991-06-28 JP JP3183769A patent/JPH07110199B2/ja not_active Expired - Lifetime
  • 1991-07-01 AU AU79460/91A patent/AU630821B2/en not_active Ceased
  • 1991-07-01 PL PL91290902A patent/PL168371B1/pl unknown
  • 1991-07-02 IN IN193/BOM/91A patent/IN171540B/en unknown
  • 1991-07-02 RU SU915001079A patent/RU2057453C1/ru active
  • 1991-07-02 CA CA002046028A patent/CA2046028A1/fr not_active Abandoned
  • 1991-07-02 HU HU912228A patent/HU213567B/hu not_active IP Right Cessation
  • 1991-07-03 ZA ZA915154A patent/ZA915154B/xx unknown
• 1993
  • 1993-04-12 US US08/046,515 patent/US5384141A/en not_active Expired - Fee Related
• 1995
  • 1995-08-31 GR GR950402405T patent/GR3017287T3/el unknown

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